PARIS—The French government is deepening its foray into shareholder activism.

On Friday, the government announced it had begun raising its stake in
Air France-KLM
AFLYY 3.26%
to nearly 18% from 16% to ensure Paris has veto power at the Franco-Dutch carrier’s next shareholder meeting.

The maneuver marks the second time in the space of a month that Paris has purchased shares to get its way in the boardroom.

In early April, Economy Minister
Emmanuel Macron
engineered a €1.2 billion ($1.35 billion) acquisition of shares in Renault SA to guarantee the state could defeat a resolution—backed by the auto maker’s board—to exempt the firm from the Florange Law, a new measure that grants double voting rights to long-term shareholders, including the government.

In announcing plans to purchase up to €45.9 million worth of shares in Air France-KLM, the French government’s goal is the same: To ensure it can outvote any shareholders who challenge the government’s push to apply the Florange Law across France Inc.

“These double-voting rights are today already a reality for the companies in which the state has a stake,” France’s Economy and Finance Ministry said.

As in the case of Renault, Air France-KLM’s board had proposed a resolution to opt out of the Florange law because some investors worried the French government was poised to acquire a disproportionate amount of influence at the Franco-Dutch carrier.

The board of Air France-KLM, however, didn’t appear on Friday to be gearing up for the kind of pitched battle that
Carlos Ghosn,
CEO of Renault and
Nissan Motor Co.
, waged against the government—and lost.

“The board considers a stable and long-term ownership structure useful to a company like Air France-KLM,” the board said, noting the cash-strapped firm in seeking a return to profitability.

The question of whether the government garners double voting rights should be settled through “shareholder democracy” at the carrier’s general assembly meeting on May 21, the board said.

The government’s shareholder activism puts a new spin on dirigisme, or government control of the economy, that defined post-World War II France. While previous economy ministers clamped down on companies by threatening to block mergers or nationalize their assets, Mr. Macron has taken a market-savvy approach.

At Renault, the government bought just enough shares to deprive Mr. Ghosn of a two-thirds majority at a key shareholder meeting. Mr. Macron also arranged options contracts to unwind the investment in Renault, after the state secured its double-voting rights. Renault’s board said the action risked undermining the health of its successful alliance with Nissan.

Paris’ push to dramatically expand its influence at Air France-KLM risks ruffling relations with the Dutch government. Under the terms of Air France’s 2004 merger with KLM, the Dutch flagship carrier continued to enjoy a high degree of autonomy and maintained separate headquarters and management board. As part of the deal, the Dutch government retained a 6% stake in KLM and handed the rest over to Air France-KLM on the condition the airline would be independently run. The Dutch government also retained, however, 50% of the voting rights.

The French government’s decision to increase its stake in Air France-KLM “is not a fundamental shift, so we don’t have a problem with it,” a spokeswoman for the Dutch Finance Ministry said.

French officials have kept their Dutch counterparts, as well as the carrier’s management, informed of the share purchase, according to a spokeswoman at the Economy Ministry. “The transaction doesn’t call into question the merger,” she said.

The government passed the Florange Law as an antidote to what Paris perceived as a growing threat: Speculative foreign investors buying French companies and hollowing out their industrial operations. The measures grants double-voting rights to investors that own shares for more than two years. A company can opt out of the regulation, however, if two-thirds of its shareholders vote in favor of the exemption.